JPH09234746A - Production of multilayered different hardeness foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce multilayered different hardness foam comfortable to sit on imparting a fit feeling to the hip of a sitting person so as to enclose the same even if a seat cushion member is relatively thin to firmly support the hip, imparting a soft feeling to the femur part of the sitting person by the front part of the cushion member without applying pressure thereto and not allowing the sitting person to feel the hardness boundary part of the cushion member. SOLUTION: The cavity 2 formed to the upper surface of a lower mold 1 is obliquely arranged so that the rear side of a seat cushion member 3 after molding becomes an underside and a raw soln. of hard first plastic foam is finely injected into the trough part 2a of the rear part of the cavity 2 in a left and right direction and, after the raw soln. of the first plastic foam is slightly foamed, a raw soln. of soft second plastic foam is injected into the central part of an upwardly inclined surface becoming the front part of the cushion member after molding in the lower mold 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of foaming a foam having a plurality of layers having different hardnesses in a foaming mold at substantially the same time.

[0002]

2. Description of the Related Art Conventionally, various methods have been disclosed, for example, in Japanese Patent Publication No. 62-37998, as a method of foam-molding a foam having a plurality of layers having different hardness almost simultaneously in one foam-molding die. Has been done.

Such a simultaneous foaming molding method is compared with a generally used method in which a plurality of layers having different hardnesses are separately molded and then adhered to each other to form a cushion body having a different hardness. In addition, the number of foaming molds is only one, and there is an advantage that the step of adhering a plurality of layers having different hardness is unnecessary and there is no possibility that the adhering surface is peeled off during use of the cushion body.

A known method of this simultaneous foam molding is to form a soft plastic foam as an upper layer which a seated person comes into contact with so as to obtain a good feeling, and a lower layer as a relatively hard plastic. It is made of foam to ensure support to the seated person, and the center part in the left-right direction is made of soft plastic foam so that a good feeling can be obtained and both sides in the left-right direction are provided. For example, some or all of the parts are formed of a relatively hard plastic foam to ensure support to a seated person.

[0005]

However, these are generally applied to automobile seats and the like having a thick molded cushion body, and these are relatively cushioned. If you try to apply it as a seat cushion for office chairs, etc. where the body is thin, the elasticity of the cushion body will change when a soft plastic foam is placed in the upper layer and a relatively hard plastic foam is placed in the lower layer. Due to the lack, the fit feeling that the seated person's buttocks are wrapped up is lacking, and the buttocks cannot be satisfactorily supported.

Further, in a case where a soft plastic foam and a relatively hard plastic foam are arranged on the surface layer of the cushion body, the occupant feels the boundary of hardness in the cushion body, and the sitting comfort is improved. It will damage.

In order to solve such a problem, an object of the present invention is to provide a seat cushion body such as an office chair having a relatively thin cushion body with a middle portion and a rear portion of the cushion body. It has a proper elasticity and gives the seated person a fit like wrapping the buttocks, can firmly support the buttocks, and the front part of the cushion body presses the thighs of the seated person. It is an object of the present invention to provide a method for producing a multi-layered foam having different hardness, which provides a comfortable soft feeling, and in which a seated person does not feel the boundary portion of the hardness of the cushion body, which is comfortable to sit on.

[0008]

According to the present invention, the above-mentioned problem is solved as follows. (1) The concave portion on the upper surface of the lower mold is arranged so as to be inclined so that the rear side of the seat cushion body after molding is the lower side, and the stock solution of the hard first plastic foam is disposed at the rear portion of the concave portion. In the valley part of the bottom, it is injected in a slender shape in the left-right direction, and after the stock solution of the first plastic foam has slightly foamed, a soft second
The undiluted solution of the plastic foam is poured into the central part of the upward inclined surface which is the front part of the cushion body after molding in the lower mold.

(2) When a cushion for a seat of a chair is molded by using a foam molding die with the upper surface side facing downward, molding in a recess provided on the upper surface of the lower mold of the foam molding die. The lower mold is arranged so that the rear side of the rear cushion body is a valley, and the stock solution of the hard first plastic foam is left and right around the center of the valley of the lower mold. In a slender direction, the stock solution of the first plastic foam slightly foams, and then the stock solution of the second plastic foam, which is softer than the first plastic foam, is placed in front of the depression of the lower mold. Is poured into the central part of the upward slope of the lower mold, and the stock solution of the second plastic foam is made to go under the stock solution of the first plastic foam from the center to the rear of the upward slope of the lower mold. , These first and second The undiluted solution of the plastic foam is foamed and cured together in the foaming mold to form a rear region of hard plastic foam, a hard plastic foam in the lower layer and a soft plastic foam in the upper layer. An intermediate transition region and a front region of soft plastic foam are formed.

[0010]

Function: The concave portion on the upper surface of the foam molding die is inclined so that the rear side of the seat cushion body after molding is on the lower side, and the stock solution of the hard first plastic foam is formed on the valley portion of the lower mold. After pouring along the left and right directions of the mold and slightly foaming it, the undiluted solution of the soft second plastic foam is injected into the central part of the upper inclined surface of the lower mold, so that the first hard plastic foam The undiluted solution of the body foams from the valley toward the upward inclined surface, and fills the valley in the foaming mold, that is, the rear part and the left and right side edges with the hard first plastic foam.

On the other hand, the undiluted solution of the soft second plastic foam foams the inclined surface radially from the center of the upward inclined surface of the lower mold, and the front portion in the foam molding die is soft plastic. Fill with undiluted foam.

When the undiluted liquids of both plastic foams start contact with each other in the stage of foaming in this way, the second plastic foam that has foamed afterwards is located at the center of the front inclined surface of the lower mold in the left-right direction. From the center in the front-rear direction to the rear, the underside of the first plastic foam is sunk.

[0013]

1 to 3 are schematic views illustrating a method for producing a multi-layered different hardness foam according to the present invention.

As shown in FIG. 1, on the upper surface of the lower mold (1) constituting the foam molding die, a concave recess (2) having a shape matching the shape of the upper surface of the seat cushion body and facing upward and upward is formed. Are formed.

As shown in FIGS. 5 and 10, the rear surface (3a) of the seat cushion body (3) is slightly raised, and the front surface (3b) is gently curved to the rear surface (3a). It is continuous.

According to the shape of the upper surface of the seat cushion body (3), the concave surface (2) of the lower mold (1) has a valley portion (2a) and a front portion (3b) corresponding to the rear portion (3a). ) Corresponding to the upper inclined surface (2b).

This lower mold (1) is placed horizontally so that its valley (2a) is the lowermost part (FIG. 1).

Next, while bringing the nozzle (4) directly above the center of the valley (2a), while pouring the stock solution of the first hard plastic foam into the valley (2a) from the nozzle (4). As shown by the arrow in FIG. 2, the nozzle (4) is moved in the left-right direction to form a pool (5) of a hard plastic foam stock solution that is long in the left-right direction in the valley (2a).

After completion of this step, the nozzle (4) is moved to the center of the upward inclined surface (2b) of the concave recess (2) as shown by the arrow in FIG.

At the time when the stock solution of the hard plastic foam, which has been injected in the lateral direction for a long time, starts to foam, the upward inclined surface (2
An undiluted solution of soft plastic foam is injected from the nozzle (4) moved to the center of (b) to form a pool (6) in the center of the recess (2).

Finally, as shown in FIG. 3, when the upper mold (7) is placed on the lower mold (1), the stock solutions (5) and (6) of the injected two kinds of plastic foams are removed. As shown by the arrow in FIG. 2, the soft stock solution that diffuses to the surroundings and is injected later is injected under the hard stock solution that is first injected and expands while foaming upward as shown in FIG. It foams while sneaking in and finally fills the space defined by the lower mold (1) and the upper mold (7).

At this time, as shown in FIG. 4, the hard stock solution diffused in the left-right direction reaches both side edges of the foaming mold and cannot spread further in the lateral direction. Form both side edges (8).

The completed cushion body (3) is, as shown in FIGS. 4 and 5, a region of hard plastic foam.
(A), a change region (B) where the hard plastic foam gradually changes to a soft plastic foam, and a region (C) of the soft plastic foam. The distribution of the hard side edges (8) in the changing region is as shown in FIGS.

The embodiment shown in FIGS. 9 to 13 is the same as the above-mentioned embodiment, except that the foaming conditions such as the composition of the second stock solution, the injection timing, and the injection amount are different. The shape of the change region (B) and the state of the second undiluted solution submerged in the finished cushion body are different.

The method of the present invention has been described in detail above. The formation state of the hard plastic foam region, particularly the side edges (8), is greatly influenced by the lateral injection length of the first stock solution. It

The second undiluted solution may not be injected at one point in the center as described above, but may be injected at the left and right portions or the like.

[0027]

【The invention's effect】

(A) A seat cushion body after molding, which is made by foaming and hardening an undiluted solution of hard and soft plastic foams in a foaming mold, is an office chair or the like having a relatively thin cushioning body. Even if it is a seat cushion body, the both side edges of the rear portion and the middle portion of the cushion body are made of hard first
It becomes a plastic foam of the above and gives a fit feeling that it is wrapped in the buttocks of the seated person by appropriate elasticity, and it is possible to firmly support the buttocks.

(B) Since the front part of the cushion body is made of soft plastic foam, it gives a soft feeling without pressing the femur of the seated person.

(C) Both of the foams have a soft second part in the middle change region in the middle of the cushion body in the left-right direction.
The upper plastic foam is the upper one and the hard first plastic foam is the lower one, and the ratio gradually changes, so that the occupant does not feel the boundary of the hardness of the two foams and is comfortable to sit on. A cushion body is obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view schematically showing a lower mold and a stock solution injection nozzle for explaining a manufacturing method of the present invention.

FIG. 2 is a plan view of the lower mold shown in FIG. 1, illustrating the diffusion of the undiluted solution of the injected first and second plastic foams.

FIG. 3 is a vertical cross-sectional view of a foam molding die showing a foam body that has completed foaming in a foam molding die composed of upper and lower molds.

FIG. 4 is a front view of the first embodiment of the seat cushion body manufactured by the manufacturing method of the present invention.

FIG. 5 is a sectional view taken along line VV in FIG. 4;

6 is a sectional view taken along line VI-VI in FIG.

7 is a cross-sectional view taken along the line VII-VII of FIG.

8 is a cross-sectional view taken along the line VIII-VIII of FIG.

FIG. 9 is a front view of a second embodiment of the seat cushion body manufactured by the manufacturing method of the present invention.

10 is a cross-sectional view taken along line XX of FIG.

11 is a cross-sectional view taken along the line XI-XI of FIG.

12 is a sectional view taken along line XII-XII in FIG.

13 is a sectional view taken along line XIII-XIII in FIG.

[Explanation of symbols]

 (1) Lower mold (2) Recess (2a) Valley (2b) Sloping surface (3) Cushion (3a) Rear (3b) Front (4) Nozzle (5) First plastic foam Stock of undiluted solution (6) Undiluted solution of second plastic foam (7) Upper mold (8) Hard side edge (A) Area of hard plastic foam (B) Change area (C) Soft plastic foam Area of the body

Claims (2)

[Claims] 1. A concave portion on an upper surface of a lower mold is arranged so as to be inclined so that a rear side of a seat cushion body after molding is a downward side, and a stock solution of a hard first plastic foam is depressed. In the valley at the back of the
After the undiluted solution of the plastic foam of above slightly foams, it is necessary to inject the undiluted solution of the second soft plastic foam into the central part of the upward inclined surface which is the front part of the cushion body after molding in the lower mold. A method for producing a multilayered foam having different hardness. 2. When molding a seat cushion of a chair by using a foam molding die with the upper surface side facing downward, after molding in a recess provided on the upper surface of the lower mold of the foam molding die. Make the rear side of the seat cushion body to be the valley part,
The lower mold is placed, and the stock solution of the hard first plastic foam is injected in a slender shape in the left and right direction around the center of the valley of the lower mold, and the stock solution of the first plastic foam is slightly After foaming into, the undiluted solution of the second plastic foam, which is softer than the first plastic foam, is poured into the center of the upward inclined surface in the front part of the recess of the lower mold to form the lower mold. The undiluted solution of the second plastic foam is made to dip below the undiluted solution of the first plastic foam from the center to the rear of the upward sloping surface, and the undiluted solution of these first and second plastic foams is expanded into By foaming and curing together in the mold, a rear region made of hard plastic foam, a hard plastic foam in the lower layer and a soft plastic foam in the middle changed region in the upper layer, Method for manufacturing a multilayer different hardness foam, characterized in that to form the front area of plastic foam.